Fortis is known to be an official supplier of watches for Russian cosmonauts. In 1995, Fortis received an order to build a chronograph with an alarm function. Based on the Valjoux 7750, Paul Geber developed a movement F2001. It is a movement with two spring barrels, but both are powered by the same rotor. The rotor is bigger and heavier than the one in 7750. For the ringing, a tone spring is mounted beneath the rotor, that is why this alarm is not very loud. 

Day of the week complication was removed and used for setting the alarm hand, "free" window was used for alarm on/off indicator instead.

Ten years later, F2001 was upgraded to F-2012, where GMT complication was added. 

Fortis was the first chronograph with the alarm complication and up to date almost the only one. Zenith was the only one that followed Fortis, and those two brands are the only ones with alarm chronographs in their offer.